1. Field of the Invention
This invention relates generally to personnel warning apparatus used for alerting workers in the path of traveling loads suspended from cranes or on moving vehicles, such as forklifts, and more particularly to a method and apparatus for selectively and personally warning only those workers in the immediate vicinity of a traveling load, especially loads passing over the worker's head.
2. General Background
Safety is a prime concern in the construction, manufacturing, and warehousing industries, especially for individuals working in the immediate vicinity of cranes or vehicles which are constantly moving various loads, often over the heads of the workers. Cranes and traveling vehicles, such as forklifts, generally sound an audible warning indicating that the crane or vehicle is traveling loaded or unloaded regardless of direction. Therefore, workers in the vicinity know the crane is moving but tend to disregard the warning since it is not specifically applicable to them most of the time. The workers simply become desensitized to the audible warnings and/or flashing lights as a result of their constant use, especially when few, if any, workers are in danger at any given time.
Ideally, only those workers who are in danger as a result of a traveling load passing in the near vicinity or overhead should be warned, giving them sufficient time to either move out of the path or at least be aware of the load's presence.
The same situation exists for back-up warning devices used on vehicles and the like. When a warning can be heard for long periods of time or seen and heard from long distances when no immediate danger exists, a certain degree of desensitivity develops. It is therefore becoming more imperative that only those workers who are being placed in immediate physical danger be warned. Some attempts has been made to automatically sence the presence of a worker who may be in harms way, as disclosed by U.S. Pat. No. 4,937,795. This system warns the vehicle operator of the presence of the worker, thereby placing full responsibility on the vehicle operator for avoiding the worker.
It is an object of the present invention to provide a system that alerts the worker only if the worker is in immediate danger and with sufficient time for the worker to take evasive action, thereby placing some responsibility on the worker for his own safety.